歐盟與南方共同市場屬於「區域對區域」的互動模式，不但促進跨區域(trans-region)與區域間(inter-region)的互動聯繫，同時強化區域內(intra-region)的深化合作。雖然歐盟與南市自由貿易協定至今仍無具體結論，但從雙邊互動的過程，仍有助於理解歐盟對外經濟治理的模式，思考區域間主義如何被運用在歐盟與南市乃至歐盟與拉美的發展上。
文章使用既有的國關理論，如現實主義的權力平衡、權力政治的觀點，自由制度主義強調的合作與複合互賴關係，以及建構主義解釋區域間互動過程中集體認同的形成，這些不同的理論要素為解釋基礎。文章以此三種理論架構詮釋區域間主義的發展，內容分為五部份：除前言外，其次分析區域間主義的類型；第三部份以現實主義、自由制度主義與建構主義觀點解釋區域間主義的動因與功能；第四部份闡述區域間主義的實踐，以歐盟與南方共同市場發展為案例解釋；第五分析歐盟南方共同市場雙邊區域間談判的互動模式與幾點觀察；最後，做出總結。 The objective of this article is to examine the type of "region-toregion" dialogue in relations between the EU and MERCOSUR. Despite the failure of the EU and MERCOSUR to sign a FTA after many years of negotiating, the relationship is crucial to a comprehensive understanding of EU strategy of external trade and how interregionalism works in practice in MERCOSUR and within Latin America.
This article uses some elements of the IR theories to explain the new approach of interregiorialism, e.g., balance of power and power relations analyzed by Realism, institution-building and agenda- setting deduced by Liberal Institutionalism, and the building of collective identity analyzed by Constructivism. The content is divided into six sections: The first section is the introduction. The second section examines the types of interregionalism. The third section deals with the functions of interregionalism based on these three theoretical frameworks . The fourth tries to understand how the EU strategy interregional approach to MERCOSUR works in practice. The fifthanalyzes the EU interaction models in MERCUSUR, and the final concludes the debates.
